1. Field of the Invention
The present invention relates generally to lock actuation devices. More particularly, the present invention relates to semiconductor film wafer cassette lock actuation devices.
2. Description of the Prior Art
Semiconductor film wafer cassettes are commonly used in the semiconductor industry for transporting semiconductor wafers or film frames that support semiconductor wafers from one semiconductor processing station to another. Additionally, the cassettes may be inserted into particular semiconductor wafer processing apparatus where individual semiconductor wafers may be manipulated and processed.
In many situations, these cassettes may have a locking mechanism for retaining one or more semiconductor wafers or film frames within the cassette while the cassette is being transported between semiconductor processing stations. The locking mechanism prevents the cassette contents from falling out. The loss of even one wafer or film frame can be economically significant. When a cassette is inserted into a semiconductor wafer processing apparatus, a lock actuation means within the apparatus will actuate or open the retaining locks, thus allowing the individual semiconductor wafers or film frames to be removed from the cassette for manipulation and processing, followed by later re-insertion by the apparatus.
A novel semiconductor film wafer cassette utilizing an opposing pair of retaining comb locking mechanisms or retaining comb locks, is disclosed in U.S. Pat. No. 5,638,958, assigned to Micron Technology, Inc., and hereinafter incorporated by reference. In the following descriptions, terms and reference numbers consistent with those employed in U.S. Pat. No. 5,638,958 are used. Furthermore, FIGS. 1B and 7 of U.S. Pat. No. 5,638,958 are reproduced below as FIGS. 1 and 2 and include additional details relevant to the descriptions below.
The semiconductor film wafer cassette 10 described in U.S. Pat. No. 5,638,958, and shown in FIG. 1, is generally comprised of a pair of opposing side panels 12 with inner surfaces 16 comprising slots 22 defined by tooth-shaped dividers 24. Semiconductor wafers or film frames (not shown) are inserted into the slots 22 and retained in the slots 22 by an opposing pair of retaining comb locks 28. The retaining comb locks 28 comprise slots 38, tooth-shaped projections 36, and hook-shaped lower flanges 34. In the normal or wafer-retaining condition in which the retaining comb locks 28 are closed, the slots 38 and tooth-shaped projections 36 of the retaining comb lock 28 are skewed or displaced relative to the slots 22 and dividers 24 of the side panel 12 of the cassette 10, so as to block the wafers or film frames from sliding out of slots 22. The tooth-shaped projections 36 thereby retain the semiconductor wafers or film frames within the cassette 10.
However, when a force opposing the downward biasing spring (not shown) of each of the retaining comb locks 28 is exerted upon the bottom surface 300 of each lower flange 34 (i.e., the actuation area 300 of the retaining comb locks 28), the pair of retaining comb locks 28 may be yieldingly urged upward to a minimum upward displacement position such that the slots 38 and tooth shaped projections 36 of the two retaining comb locks 28 are aligned with the slots 22 and dividers 24 of the side panels 12 of the cassette 10. This displaced position allows sliding removal of the film frames or wafers from the cassette 10. The dual comb locks 28 provide a measure of security relative to a single lock, because their actuation areas 300 are separated from each other, and both locks 28 must be actuated to release a film frame or wafer. Accidental release of one comb lock 28 is insufficient to release a film frame or wafer.
As described above, this actuation or opening of the pair of retaining comb locks 28 will usually be performed by a lock actuation means within a particular semiconductor wafer processing apparatus. However, prior to inserting or providing the cassette 10 to a processing apparatus, it may be desirable to remove manually some or all of the semiconductor wafers or film frames from the cassette 10 or to insert additional semiconductor wafers or film frames into the cassette 10. In order to remove or insert the semiconductor wafers or film frames, both retaining comb locks 28 of the cassette 10 must be temporarily actuated or opened. Thus, the security of having dual locks becomes a disadvantage, because it may take one hand to release each lock 28 (and keep it released), leaving no hand for handling the wafers or film frames.
One prior device for temporarily actuating or opening the retaining comb locks 28 of a cassette 10 is shown in FIGS. 3 and 4. As shown in FIG. 3, the device 100 is generally an inverted T-shaped bar comprising a base 102 and a raised center member 104. The base 102 provides stability for the device 100 while the raised center member 104 contacts the two actuation areas 300 of the retaining comb locks 28 as shown in FIG. 4. The device shown in FIGS. 3 and 4 may, however, be relatively difficult to operate. In most cases, an operator must use two hands to operate the device 100; one hand to hold the device 100 steady beneath the cassette 10 in alignment with both actuation areas 300, and the other hand to lower the cassette 10 onto the device 100 such that both actuation areas 300 of the retaining comb locks 28 are engaged by the raised center member 104. While the operator is lowering the cassette 10 onto the raised center member 104 of the device 100, the operator must ensure that the device 100 is properly aligned, such that both retaining comb locks 28 are simultaneously actuated or yieldingly urged upward by the raised center member 104.
Another device for temporarily actuating or opening the retaining comb locks 28 of a cassette 10 is shown in FIGS. 5A-B and 6. The device 200 generally comprises a pair of structurally connected, parallel, symmetrically-opposed guide rails 202, as shown in FIG. 5A. As shown in FIG. 5B, the guide rails 202 (only one is shown; the other is a mirror image of the first) comprise a flange 204, a slot 206 and an inclined portion 208. The flanges 204 are adapted such that the bottom portion 302 of each of the side panels 12 of the cassette 10 may be inserted and slidably retained in the slot 206. As shown in FIG. 6, as the bottom portion 302 of each cassette's side panel 12 is further inserted into the slot 206, a portion of the actuation area 300 of the lower flange 34 of the retaining comb locks 28 engages and is yieldingly urged upwards by the relative vertical increase of the inclined portion 208 of the guide rail. This occurs simultaneously with both locks 28, as the bottom portions 302 are inserted further into the parallel slots 206. If the bottom portion 302 of the side panels 12 is inserted such that the actuation area 300 reaches point 210 of the inclined portion 208, the retaining comb locks 28 will reach the minimum upward displacement and be in the actuated or open position. However, this device 200, similar to the device 100 described above, may be relatively difficult to operate. Again, similar to the device 100 described above, an operator must generally use two hands to operate the device 200; one hand to steady the device 200, and the other hand to slidably insert the bottom portion 302 of each of the side panels 12 of the cassette 10 into the slots 206 of the opposing guide rails 202. Furthermore, due to differences in the width of cassettes 10, the distance between the parallel, opposing guide rails 202 may need to be varied to accommodate different cassettes.
Thus, there exists a need for a lock actuation device that is easy to use. There also exists a need for a lock actuation device that is relatively quick to operate, thus, saving production time and operating expenses. Furthermore, it is desirable that the device be relatively easy to align and to operate with one hand.